In newer generation vehicle radar systems, a high degree of integration is sought, which means that circuits previously realized discretely are increasingly replaced by IC solutions. In the area of microwave technology, the trend is towards MMIC solutions (MMIC=monolithic microwave integrated circuits). One problem here is the testability of the individual MMICs. Performing the tests has to ensure, on the one hand, that the produced circuits correspond to the specifications in their individual parameters, on the other hand, such tests represent a cost-intensive factor in the production of such integrated circuits.
It is precisely the performance of tests for high frequency integrated devices, such as at frequencies in the range of 80 GHz in the vehicle radar technology, that involves much effort and cost. In vehicle radar systems, there are often used DROs (oscillators with dielectric resonator). These devices have a high resonator quality and thus result in very high spectral purity. Testing such DROs proves to be problematic, since the corresponding tests generally cannot be performed as on-wafer test (OW test), because, in a DRO, the frequency-determining element is typically a dielectric pill that is coupled off-chip to the oscillator core. For this reason, performing an OW test of the corresponding chip is only possible with restrictions during the production.